1. Field of the Invention
This invention relates to a method and apparatus for optimizing performance of a device such as a motor, and particularly to an improved method and apparatus for optimizing a control module that controls performance of the device.
2. Description of the Related Art
In the past, optimal values of a characteristic of a control module (namely, parameter values for deciding input-output relationship of the control module) to control a controlled system were determined prior to shipment by experiment during design or assembly, so that users of a product comprising a controlled system were assumed and the users"" characteristics (preference, technique, personality, and use) could be met.
However, with the diversity and advancement of recent technology, the conventional method of deciding optimal values of a characteristic of the control module by experiment brings about difficulty for optimizing the control module, and requires a lot of time.
Since personal characteristics or preferences vary from one person to another, the conventional control method cannot provide a characteristic of products which satisfy all users.
In view of the problems described above, a para-evolutionary method has been proposed. In this method, a control apparatus produces a plurality of chromosomes by using control parameters of the control apparatus that exert influence on characteristics of a controlled subject or machine. Some of the chromosomes evolve by a genetic algorithm by selecting favorable chromosomes based upon intention of the user.
The machine used in the above method is operated with the respective chromosomes that are initially produced. The user evaluates the respective operations to reject undesirable chromosomes. Characteristics appropriate to the user can be obtained using this method. However, it is difficult for the user to evaluate subtle changes solely by his or her bodily sensations. For instance, if the method is employed in a control system for an automobile, feelings such as a feeling of subtle differences in acceleration cannot easily be evaluated by a driver because they are unseen. To resolve this problem, another method has been proposed in which a control apparatus links the characteristics of the machine with rectangular patterns and shows the patterns at every chromosome on a display for providing additional information to the user to assist the user""s evaluation by his or her bodily sensations.
However, even using this last method, it is still difficult for the user to intuitively grasp the relationships between rectangular patterns and the characteristics of the machine being controlled. The user must learn the relationships by referring to an operating manual or instruction book. This increases the burden on the user. In addition, since the relationships are not intuitive, the user may make mistakes in the evaluation during the optimization process. The mistakes made during optimization may result in the control apparatus responding in a way that deviates from the desired response. Moreover, a number of machines that need the optimization require slow changes in characteristics so that they will not change abruptly in actual operations. Hence, the user may not notice the deviation soon enough. As a result, the control apparatus needs a relatively long period of time.
It is, therefore, a principal object of the present invention to provide a method and apparatus for optimizing overall characteristics by which the user can intuitively grasp characteristics during the optimization process and eliminate mistakes in evaluation.
The present invention, which is directed to the above-described object, provides a method for controlling performance of a device manipulated by a user. The performance is essentially controlled by at least one control module having an input-output relationship regulated by control parameters, said method comprising the steps of: (a) preselecting values of the control parameters and activating the device; (b) on-line changing values of the control parameters within predetermined ranges under predetermined coding rules; (c) on-line evaluating the performance of the device based on signals indicative of the performance; (d) on-line displaying to the user the evaluation outcome in the form of intuitively recognizable symbols which are preselected to represent various evaluation outcomes; (e) on-line selecting values of the control parameters based on the selected symbol(s) by the user; and (f) repeating steps (b) through (e) while operating the device until desired performance of the device is demonstrated, wherein the at least one control module is optimized. According to the above, a user can intuitively respond to progress of changes in performance of the device, thereby optimizing the performance. No special skills are required.
In the above, optimization is conducted xe2x80x9con-linexe2x80x9d, i.e., on a real-time basis. Additionally, in one embodiment, pre-optimization is conducted before operating the device, by using the intuitively recognizable symbols.
In another embodiment, the display of the intuitively recognizable symbols changes in accordance with the number of times the cycles of steps (b) through (e) are repeated. According to this embodiment, efficient optimization can be performed by efficiently selecting the symbols.
The display may comprise, in the alternative, visual signals, auditory signals, and tactile signals. The intuitively recognizable symbols may be selected from the group consisting of plants, fish, birds, mammals and living bodies including worms. Alternatively, the intuitively recognizable symbols may be selected from the group consisting of facial expressions and body types.
In one embodiment, optimization is conducted by heuristic processes; that is, step (b) can be conducted using heuristic processes programmed to change values of the control parameters toward a direction of obtaining rewards which are defined by the result of selection by the user in step (e). The heuristic processes include evolutionary computing, such as genetic algorithms. For example, in one embodiment, wherein the control module comprises at least one neural network and the input-output relationship is regulated by coupling coefficients used as the control parameters, step (b) may be conducted by genetic algorithms programmed to form chromosomes containing genes encoding coupling coefficients (the genes being selected to avoid acute changes in the encoded coupling coefficients), and step (e) may be conducted by selecting chromosome(s).
Plural control modules can be used in an embodiment, and when the device""s performance is characterized by at least two elements, the control modules are directed to the respective characteristic elements. In the above, optimization by steps (a) through (e) can be conducted on each control module in repetitive sequence. According to this embodiment, overall characteristics of the performance can be optimized.
In the present invention, the device may include a control module for controlling another device. That is, the present invention can be adapted for optimizing a control module which controls another control module. In such embodiments, the device includes a motor (e.g., an electronically controllable driving device including an internal combustion type or electric type), and non-driving device such as computers.
For purposes of summarizing the invention and the advantages achieved over the prior art, certain objects and advantages of the invention have been described above. Of course, it is to be understood that not necessarily all such objects or advantages may be achieved in accordance with any particular embodiment of the invention. Thus, for example, those skilled in the art will recognize that the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein.
Further aspects, features and advantages of this invention will become apparent from the detailed description of the preferred embodiments which follow.